Pipe bending apparatus



Wv G HARDY PIPE BENDING APPARATUS Feb. 28, 1939.

3 Sheets-Sheet 1 Filed March 6, 1937 INVENTOR Feb. 28, 1939. we. HARDY I PIPE BENDING APPARATUS Filed MaYGh 6, 1937 3 Sheets-Sheet 2 Feb. 28, 1939. w G, HARDY 2,148,748

PIPE BENDING APPARATUS Filed March 6, 1937 33 40 I 20 37 \I H y w W" 3 Sheets-Sheet 3 Patented Feb. 28, 1939 UNITED STATES PATENT OFFICE PIPE BENDING APPARATUS tion of Pennsylvania Application March 6,

4 Claims.

My invention relates to the bending of metal tubes and has for its object the provision of means for bending tubes in such manner that wrinkling or buckling of the metal at the inner 5 side of the bend is avoided, and whereby flattening or excessive stretching of the metal at the outer side of the bend is prevented.

Apparatus for practicing my invention is shown in the accompanying drawings wherein Figure 1 is a plan view thereof; Fig. 2 is a side elevational View; Fig. 3 is a View taken on the line IlI-III of Fig. 2; Fig. 4 is an enlarged View taken on the line IVIV of Fig. 1; Fig. 5 is a plan view of the structure of Fig. 4; Fig. 6 shows the apparatus of Fig. 5 in another position, and Fig. '1 is a View taken on the line VII-VII of Fig. 5.

The apparatus includes a base frame 8 upon which is mounted a base plate 9 having a slideway in which a slide plate It is mounted for '20 reciprocal movement longitudinally. of the base plate. The slide plate 50 has a projection I 1 extending downwardly through a slot in the base plate 9. A cylinder i2 is bolted to the under side of the base plate 9 and contains a piston l3 to which is connected a piston rod [4 that has connection with the projection l I. When fluid pressure is admitted through a pipe [5 to the rear side of the piston, the slide plate l will be advanced, while fluid pressure admitted through a pipe I6 will effect retraction of the slide plate.

At its forward end, the base plate 9 is provided with a supporting block 18 to which is secured a die 20 by suitable screws or bolts 2|. The die is provided with a grooved nose portion 22 for receiving the tube and about which the tube is shaped, as hereinafter described. The nose of the die 20 is spaced a sufiicient distance above the bed plate 9 to permit the forward end of the slide l0 and a pivot pin 23 carried thereby to be moved beneath the same, as shown in Figs. 2 and 4.

Arms 24 and 25 are pivotally conneoted at their forward ends to the pivot pin 23 and at their rear ends have connection with links 26, whose other ends are pivotally connected at 21 to a slide block 28. The slide block 28 issupported in a slide way 29 which is bolted to the slide plate Ill.

A piston rod 36 is connected to the slide block 28 and has connection with a piston contained within a cylinder 3| which is bolted to a cover plate 32 which overlies the rear end of the slide plate Ill. It will be understood that when pressure is admitted to the ends of the cylinder 3| in succession, the links 26 and the arms 24 and 25 will be oscillated, the links 26 and their associated arms having toggle-like movement. Each 1937, Serial No. 129,410

of the arms 24 and 25 carries a die block 33 that is loosely supported therein by suitable guide Ways, for limited sliding movement in directions longitudinally of the blocks. Each of the blocks 33 has a depending lug 35 that abuts against the inner side of its associated arm, so that the blocks cannot slide outwardly from the arms and whereby the blocks are caused to assume their centralized positions shown in Fig. when the arms are retracted from their positions in Fig. 6 to their positions in Fig. 5.

A roller segment 36 is pivotally mounted on the arm 24 in position to roll on the adjacent die block 33 when the parts are moved from the position shown in Fig. 5 to that shown in Fig. 6. Similarly, a segmental roller 31 is pivotally mounted on the arm 25 in position to have rolling movement on its associated block 33. Each of the rollers 36 and 31 has a depending lug 38 that engages the inner edge of its associated arm, so that the rollers will be stopped at their initial positions when the parts are'swung from the position shown in Fig. 6 to the position shown in Fig. 5. The axes ,of the rollers 36 and 31 are in radial alignment with the center of the stationary die 20 and with the inner ends of the die blocks 33.

Starting with the bending dies in expanded position, as shown more clearly in Figs. 1, 2 and 5, a tube 40 is inserted between the stationary die 20 and the die blocks 33. Thereupon fluid pressure is admitted to the cylinder 12 to advance the slide plate I0 to align the axis of the pin 23 and the center of the die 20 and thereby bring the die blocks 33 into engagement with the tube and move it into the groove 22 of the stationary die 20. Pressure is thereby exerted on the tube adjacent to and symmetrically with a line intersecting the axes of the rollers 36 and 31 and extending through the center of the stationary die 20, this pressure being transmitted through the rollers 36 to the die blocks 33, whereby the tube is firmly clamped between the die blocks 33 and the die 2|] at the point of tangency of the tube with the die 20. The inner edges of the rollers 36 and 31 have engagement with the inner ends of the die blocks, the roller 31 having its segment extended to a point nearly in alignment with the axes of the rollers, as shown more clearly in Fig. 5.

Fluid pressure is then admitted to the rear end of the cylinder 3|, to cause the slide block 28 to advance and effect spreading of the links 26 and the arms 24 and 25. This spreading movement rocks the blocks 33 and causes the rollers 36 and 31 to roll along the blocks and hold them firmly against the tube 40 at points radially of the die 20. The blocks 33 are somewhat loose in their slide Ways, so that the arms 24 and 25 can move outwardly relative to the blocks, as will be apparent from a comparison of the relative positions of the slide blocks and the arms, as shown in Figs. 5 and 6. During this relative sliding movement of the arms and the die blocks 33, and while the members 36 and 31 are rolling along the die blocks, I have found it desirable to maintain the pressure in the cylinder I2 during this stage of the bending operation, so as to maintain proper clamping engagement of the bending dies with the tube.

It will be seen that there is little or no sliding movement of the die blocks on the tube such as would tend to score or tear the metal, and that the bending forces are applied over wide areas extending throughout substantially the entire lengths of the blocks 33. The apparatus is particularly efiective in the bending of thin-walled tubing, where it is desirable not only to prevent undue distortion of the metal, but where smoothness is desirable for the sake of appearance, as, for example, in the making of tubular furniture. The invention, however, also is useful in the bending of thick-walled tubing where smoothness of shape or contour is desired.

I claim as my invention:

1. Tube bending apparatus comprising a die having a convex grooved surface, a pair of die blocks disposed in opposed relation to said die and arranged end-to-end, an arm carrying each of said blocks and pivoted adjacent to the said die, means supporting each block upon its arm, for relative sliding movement longitudinally of the block, a segmental roller on each arm, in position to engage the rear side of its associated block and to have rolling movement thereon during said relative sliding movement, and means for swinging said arms, to impart rocking movement to the blocks, in directions to bend a tube against said convex surface, the adjacent ends of the segmental surfaces of the rolls being approximately in abutting engagement at the initial positions of the parts.

2. Tube bending apparatus comprising a stationary die having a convex grooved surface, a slide plate reciprocable relative to said stationary die, a pair of die blocks pivotally mounted on said plate and disposed in end-to-end relation, means for imparting rocking movement to said blocks in directions to bend a tube against said convex surface, and means for simultaneously urging the said plate toward the stationary die.

3. Tube bending apparatus comprising a die having a convex grooved surface, a slide plate, a pair of arms pivotally mounted on said plate, a die block carried by each of said arms, the blocks being mounted in end-to-end relation, means on the Said plate for oscillating said arms to impart rocking movement to the die blocks and bend a tube around said convex surface, and means for simultaneously urging the slide plate toward the stationary die.

4. Tube bending apparatus comprising a die having a convex grooved surface, a pair of die blocks disposed in opposed relation to said die and arranged end-to-end, an arm carrying each of said blocks and pivoted adjacent to the said die, means supporting each block upon its arm, for relative sliding movement longitudinally of the block, a roller on each arm, in position to engage the rear side of its associated block and to have rolling movement thereon during said relative sliding movement, and means for swinging said arms to impart rocking movement to the blocks, in directions to bend a tube against said convex surface, the said rollers being formed to initially engage said blocks at the adjacent ends thereof, and their axes being intersected by a line which extends perpendicularly to the mid point of said grooved surface and between the adjacent ends of the die blocks.

WILLIAM G. HARDY. 

